Single-phase heat transfer in microchannels The importance of scaling effects

By P. Rosa, T. Karayiannis, M. Collins. 2009

297 citations recorded by the source corpus.

Microscale single-phase heat transfer is widely used in industrial and scientific applications and for this reason, many related papers have been published in the last two decades. Nevertheless, inconsistencies between published results still exist and there is no generally accepted model for the prediction of single-phase heat transfer in microchannels. This paper presents a review of the experimental and numerical results available in the open literature. Heat transfer in microchannels can be suitably described by standard theory and correlations, but scaling effects (entrance effects, conjugate heat transfer, viscous heating, electric double layer (EDL) effects, temperature dependent properties, surface roughness, rarefaction and compressibility effects), often negligible in macro-channels, may now have a significant influence and have to be accounted for. Furthermore, measurement uncertainties may be more important, due to the reduced characteristic dimensions, so have to be accurately checked and, where possible, reduced. Experiments with single channels are more accurate and in good agreement with predictions from published correlations, in contrast to multi-(parallel) channel experiments. The latter are subject to maldistribution, 3D conjugate heat transfer effects and larger measurement uncertainties. Sub-continuum mathematical models for fluid dynamics are briefly reviewed and explained. These models are expected to gain a growing interest in the near future due to the rapid descent of microchannel dimensions down to the nano-scale. The paper concludes with a concise set of recommendations for purposes of performance and design. For single channels, available correlations for macro-channels can also give reliable predictions at the micro-scale, but only if all the scaling effects can be considered negligible. Otherwise, when scaling effects cannot be neglected or for the case of heat exchangers with parallel channels, suitable numerical simulations may be the sole alternative to carefully designed experiments to evaluate the heat transfer rates.

Subfields: Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/d009ca429002396bfc3896a7c47d30659074b6af

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In Mechanical Engineering

Citations in the corpus

Heat transfer enhancement in microchannel heat sinks with periodic expansion–constriction cross-sections (2013, unknown): “[3] presente d a review of the experime ntal and numerical results”
History, Advances, and Challenges in Liquid Flow and Flow Boiling Heat Transfer in Microchannels: A Critical Review (2012, background): “Excellent review articles covering the developments in microchannel research, giving the details of experiments, their uncertainty levels, and model/correlation descriptions have been published periodically and readers are encouraged to read these for an exhaustive coverage of the earlier work [2–28”
A review on heat transfer and hydrodynamic characteristics of nano/microencapsulated phase change slurry (N/MPCS) in mini/microchannel heat sinks (2018, unknown): “[18] comprehensively discussed the scaling effects 22 (entrance effects, conjugate heat transfer, viscous heating, electric double layer effects, temperature 23 dependent properties, surface roughness, rarefaction and compressibility effects) on thermo-hydraulic 24 characteristics of single phase fl”